.caculator {
    text-align: center;
    width: 232px;
    border:1px solid #000;
    overflow: hidden;
    border-radius: 10px;
    background-color: #292a29;
    font-weight: normal;
   
  }
  * {
    box-sizing: border-box;
  }
  .result-table {
    height: 80px;
    line-height: 80px;
    padding: 0 10px;
    font-size: 40px;
    text-align: right;
    color: white;
  }
  
  .operation-table {
    font-size: 0;
    margin: 0 -1px -1px -1px;
  }
  
  .block {
    display: inline-block;
    width: 25%;
    height: 50px;
    line-height: 50px;
    text-align: center;
    font-size: 24px;
    border-width: 0 1px 1px 0;
    border-style: solid;
    border-color: #2196f3;
    color: #fff;
    cursor: pointer;

  }
  button.block:active {
    opacity: 0.5;
  }
  button.block.block--ctrl {
    background-color: #3e3f3e;
  }
  button.block.block--num {
    background-color: #5e5f5e;
  }
  button.block.block--exp {
    background-color: #fd8d0e;
  }
  button.block--double {
    width: 50%;
  }
  